The preferred embodiment concerns a modulator for radio-frequency signals, wherein:                the modulator is designed as a completely digital modulator,        the modulator has a mixer stage,        a modulation signal and an oscillator signal are supplied to the mixer stage a sample rate,        the mixer stage mixes the modulation signal and the oscillator signal into a final signal and outputs the final signal with the sample rate,        the oscillator signal is generated by an oscillator,        the oscillator has a phase accumulator and a phase-amplitude transducer,        the oscillator signal possesses an oscillator frequency,        wherein the oscillator frequency is determined by an incremental value by which the content of the first phase accumulator is incremented between two readout processes in immediate succession,        the incremental value has a bit width.        
For example, such a modulator is known from the DAC 5687 by Texas Instruments.
For the operation of magnetic resonance systems, a radio-frequency signal that can be adjusted in frequency and amplitude (also in phase, given pulse series) is required to excite the spins. For this purpose, a low-frequency envelope is normally converted to an intermediate frequency and then to the operating frequency (Larmor frequency) by means of complex modulation to generate a single sideband. For multichannel transmission systems, many individually adjustable radio-frequency signals are required (corresponding to the number of transmission channels). Furthermore, alternating pulses with frequencies differing from one another are sent in what are known as decoupling experiments, wherein the pulses must, however, remain phase-locked relative to one another.
In previous concepts, the low-frequency signal or the intermediate frequency signal is converted into an analog signal, and then the converted signal is translated to the radio-frequency by means of analog single sideband modulation. However, the analog mixer stages require a complicated compensation for the sideband and carrier suppression. Furthermore, precision mixers are required. Both techniques (compensation and use of precision mixers) are very cost-intensive. The corresponding components are required multiple times for multichannel systems, whereby the expenditure and the costs increase even further.